Minutes for Telecon for Mar 12, 2002

Present: Churchwell, Whitney, Watson, Meade, Stolovy, Dickey, Marston,
Indebetouw, Babler, Kobulnicky, Wolff, Benjamin, Ashman, Jackson

Team meeting in Madison  March 21 & 22, 2002
Next telecon: Tuesday April 9, 2002, 11 am CST, 608-265-1000 #4112

Science Specification Document 
Discussion Points - Remy

  Science Drivers - 

   - Ed, Barb and Tony have contributed so far.
   - Galactic structure group has been hung up on ISO calibration issues
   - Bob has been looking at the colors of C stars, AGB stars, OH-IR.
     He still needs to look at distances...we need breakpoints, how to
     identify objects.

  Data processing issues

   - Saturated stars need to be pre-processed...remove PSF wings. Remy
     has written a routine that fits to the PSF wings. Flux is precise to a 
     few %.  Will probably have multiple overlapping in dense clusters of
     saturated sources. May be able to extract info from saturated source

   - Source matching/band merging
     In a crowded field, matching based on proximity alone can give false matches.
     Remy's routine does it in an ordered way in brightness, starting with
     bright sources.  We have acquired DAOMATCH and DAOMASTER from Stetson.
     It does triangle matching.  We will compare the methods.
     There may be a bias in looking for similar flux levels.
 
   - Mosaicing
     We have only 2 passes.  For 2-point dither, Remy's been using a drizzle
     parameter of 0.75.  We'd like to check out the science verification obs.
     with simulations.

   - Flux Calibration
     We are assuming we are not changing SSC's calibration but we will
     do spot checks using Cohen's flux calibrators and consult with SSC
     if there are inconsistencies. There are several objects of known spectral
     types in the Science Verification Observation region W51.  Can Martin
     give us some calibrators- particularly in the W51 region?  We're trying to 
     get $$ support for him.  The Michigan Spectral Atlas doesn't cover the 
     northern hemisphere.  With WIYN, W51 is visible late July/early August.
     Maybe a project for a summer student?

  General Questions about what and how we will report sources

   - Should we report a local background and/or local source density?
     can calculate the source density from the starlist. have the pipeline
     report it.  DAOPHOT automatically reports local bkg.

   - Should we report a single flux for the BSC and one for the PSC,
     using the best combination of the two passes and mosaiced image,
     or should we report all of the different internally calculated fluxes?
     if a variable, if only report one number, the variability info is lost.
     Report one number but flag info if there are differences between the
     2 passes.  If we do the half-step observing stratgey, then report 
     one number.  If 2 visits separated in time, may want both numbers?
     2 visits would be good for issues of variability, banding and if
     the dither in the 1/2 step is not enough.  Chip & Christer will look
     into the efficiencies between the 1/2 step and 2 visit strategies
     when a new version SPOT is released (mid-April).

   - Our current pipeline will produce different fluxes for sources that are
     in both the BSC and PSC (they will agree to within error or we will
     increase the error). 

   - Current plan is to band-fill (upper limits on sources not seen in all
     bands) the PSC. Do aperture photometry with DAOPHOT.  BSC also?

   - Positional accuracy: use 2MASS positions (0.1" accuracy) to improve our
     positional accuracy.  For science and data products points of view, we
     want to do it.  SSC will do 1.4" accuracy from spacecraft info.
     After the fact, can do pointing reconstruction.  There is fits header
     info for the distortion keywords on the IRAC interest group web site.
     The distortion keywords have been finalized.

Survey tracker - Christer

     Primary interface will be html page. One for public and one for team.
     Can input coordinates (RA, Dec or l, b) or put in boundaries.
     Choose which data to plot (observed, at each of the pipeline levels (A,B,C,D,E) -
      hung, failed, passed)
     Default is survey region with a map of what has been done.  Then can choose, for
     example, "hung at B", then get data that have been hung up at level B processing.
     Use IDL to make plots.  Give back a gif file and link to a ps file.
     Include a zoom feature.  If want to recenter, can do on the fly?
     Access database once a day to get observing and reduction information.
     Hopes to get a first cut of the interface by the March 21-22 Madison meeting.
     Jim notes that the 13CO survey website has some nice features.  Robert Simon
     is the contact person.